Contrary to popular belief, the basilica does not hold the distinction in the Roman Catholic Church of being the ecumenicalmotherchurch, as it is not the cathedral of the Pope (in fact, it is not a cathedral at all). That distinction belongs to the Basilica di San Giovanni in Laterano. However, due to the proximity of the Papal residence, most Papal ceremonies take place at St. Peter's. The basilica also holds a relic of the Cathedra Petri, the episcopal throne of the basilica's namesake when he led the Roman church, but which is no longer used. These are the sources of the confusion.

History

The Second Vatican Council convened in the Basilica of Saint Peter. The high canopy or baldocchino was designed by Bernini.

The current location is probably the site of the Circus of Nero in the first century. After Emperor Constantine officially recognized Christianity he started construction in 324 of a great basilica in this exact spot, which had previously been a cemetery for pagans as well as Christians.

In the mid-15th century it was decided that the old basilica should be rebuilt. Pope Nicholas V asked architect Bernardo Rossellino to start adding to the old church. This was abandoned after a short while. In the late 15th centuryPope Sixtus IV had the Sistine Chapel started nearby.
.
The basilica in itself is an artwork composed of many valuable artistic elements. Construction started under Pope Julius II in 1506 and was completed in 1615 under Pope Paul V. Donato Bramante was to be the first chief architect. Many famous artists worked on the "Fabbrica di San Pietro" (as the complex of building operations were officially called). Michelangelo, who served as main architect for a while, designed the dome. After the death of Julius II building was halted until Pope Paul III asked Michelangelo to design the rest of the church. After Michelangelo's death his student Giacomo della Porta continued with the unfinished portions of the church. Carlo Maderno became the chief architect later on, and designed the entrance.

Details

Directly to the east of the church is the elliptical St. Peter's Square (Piazza San Pietro), built between 1656 and 1667, in the center of which is a 25.5 meter tall obelisk. The obelisk was moved to its present location in 1585 by order of Pope Sixtus V. The obelisk dates back to the 13th century BC in Egypt, and was moved to Rome in the 1st century to stand in Nero's Circus some 275 yards away. Including the cross on top and the base the obelisk reaches 40m. On top of the obelisk there used to be a large bronze globe allegedly containing the ashes of Julius Caesar, this was removed as the obelisk was erected in St. Peter's Square. There are also two fountains in the square, the south one by Maderno (1613) and the northern one by Bernini (1675).

The dome designed by Michelangelo was completed by Giacomo della Porta in 1590.

The dome or cupola was designed by Michelangelo, who became chief architect in 1546. At the time of his death (1564), the dome was finished as far as the drum, the base on which domes sit. The dome was vaulted between 1585 and 1590 by the architect Giacomo della Porta with the assistance of Domenico Fontana, who was probably the best engineer of the day. Fontana built the lantern the following year, and the ball was placed in 1593.

As built, the double dome is brick, 42.3 metres in interior diameter (almost as large as the Pantheon), rising to 120 metres above the floor. In the early 18th century cracks appeared in the dome, so four iron chains were installed between the two shells to bind it, like the rings that keep a barrel from bursting. (Visitors who climb the spiral stairs between the dome shells can glimpse them.) The four piers of the crossing that support it are each 60 feet (18 meters) across. It is not simply its vast scale (136.57 meters from from the floor of the church to the top of the added cross) that makes it extraordinary. Michelangelo's dome is not a hemisphere, but a parabola: it has a vertical thrust, which is made more emphatic by the bold ribbing that springs from the paired Corinthian columns, which appear to be part of the drum, but which stand away from it like buttresses, to absorb the outward thrust of the dome's weight. The grand arched openings just visible in the illustration but normally invisible to viewers below, enable access (not to the public) all around the base of the drum; they are dwarfed by the monumental scale of their surroundings. Above, the vaulted dome rises to Fontana's two-stage lantern, capped with a spire.

The egg-shaped dome exerts less outward thrust than a lower hemispheric one (like Mansart's at Les Invalides) would have done. The dome conceived by Donato Bramante at the outset in 1503, was planned to be carried out with a single masonry shell, a plan that was discovered not to be feasible. San Gallo came up with the double shell, and Michelangelo improved on it. The piers at the crossing which were the first masonry to be laid, which were intended to support the original dome, were a constant concern, too slender in Bramante's plan, they were redesigned several times as the dome plans evolved.

Above the main entrance is the inscription IN HONOREM PRINCIPIS APOST PAVLVS V BVRGHESIVS ROMANVS PONT MAX AN MDCXII PONT VII (In honor of the prince of apostles; Paul V Borghese, pope, in the year 1612 and the seventh year of his pontificate). The fa硤e is 114,69 metres wide and 45,55 m high. On top are statues of Christ, John the Baptist, and eleven of the apostles; St. Peter's statue is inside. Two clocks are on either side of the top, the one on the left is electrically operated since 1931, with its oldest bell dating to 1288.

The northernmost door is the "Holy Door" in bronze by Vico Consorti (1950), which is by tradition only opened for great celebrations such as Jubilee years. Above it are inscriptions. The top reads PAVLVS V PONT MAX ANNO XIII, the one just above the door reads GREGORIVS XIII PONT MAX. In between are white slabs commemorating the most recent openings:

Interior

The Holy Doors are opened during jubilees proclaimed by the Pope.

Walking along the right aisle of the basilica, there are several noteworthy monuments and memorials. The first is Michelangelo's Piet১, located immediately to the right of the entrance. After an incident in 1972 when an individual damaged it with an axe, the sculpture was placed behind protective glass. Up the aisle is the monument of Queen Christina of Sweden, who abdicated in 1654 in order to convert to Catholicism. Further up are the monuments of popes Pius XI and Pius XII, as well as the altar of St Sebastian. Even further up is the Chapel of the Blessed Sacrament, which is open during religious services only. Inside it is a tabernacle on the altar resembling Bramante's Tempietto at San Pietro in Montorio. Bernini sculpted this gilded bronze tabernacle in 1674. The two kneeling angels were added later. Further still are the monuments of popes Gregory XIII (completed in 1723 by Carlo Rusconi) and Gregory XIV.

In the northwestern corner of the nave sits the statue of St. Peter Enthroned, attributed to late 13th century sculptor Arnolfo di Cambio (with some scholars dating it back to the 5th century). The foot of the statue is eroded due to centuries of pilgrims kissing it. Along the floor of the nave are markers with the comparative lengths of other churches, starting from the entrance (not an original detail). Along the pilasters are niches housing 39 statues of saints who founded religious orders.

Walking down the left aisle there is the Altar of Transfiguration. Walking down towards the entrance are the monuments to Leo XI and Innocent XI followed by the Chapel of the Immaculate Virgin Mary. After that come the monuments to Pius X and Innocent VIII, then the monuments to John XXIII and Benedict XV, and the Chapel of the Presentation of the Blessed Virgin. After that comes the Monument to the Royal Stuarts, directly opposite the one to Maria Clementina Sobieska. Symmetrically, the two monarchs who gave up their thrones for their Catholic faith in the 17th century, are honored side by side in the most important church in Catholicism. Finally, right before the end of the church, is the Baptistry.

Over the main altar stands a 30 m (90 ft.) tall baldachin held by four immense pillars, all designed by Bernini between 1624 and 1632. The baldachin was built to fill the space beneath the cupola, and it is said that the bronze used to make it was taken from the Pantheon. Underneath the baldachin is the traditional tomb of St. Peter. In the four corners surrounding the baldachin are statues of St Helena (northwest, holding a large cross in her right hand), St Longinus (northeast, holding his spear in his right hand), St Andrew (southeast, spread upon the cross which bears his name) and St Veronica (southwest, holding her veil). The statue of Longinus is by Bernini (1639) and the others are by his followers. Each of these statues represents a relic associated with the person, respectively, a piece of The Cross, the Spear of Destiny, St Andrew's head (as well as part of his cross) and Veronica's Veil. In 1964, St Andrew's head was returned to the Greek Orthodox Church by the Pope. It should be noted that the Vatican makes no claims as to the authenticity of several of these relics, and in fact other Catholic churches also possess "the same" relics. Along the base of the inside of the dome is written, in letters 6 ft. (2 m) high, TV ES PETRVS ET SVPER HANC PETRAM AEDIFICABO ECCLESIAM MEAM. TIBI DABO CLAVES REGNI CAELORVM (Vulgate, from Template:Bibleverse; "...you are Peter, and on this rock I will build my church. ... I will give you the keys of the kingdom of heaven...."). Near the top of the dome is another, smaller, circular inscription: S. PETRI GLORIAE SIXTVS PP. V. A. M. D. XC. PONTIF. V. (To the glory of St. Peter; Sixtus V, pope, in the year 1590 and the fifth year of his pontificate).

The Chair of Saint Peter, Cathedra Petri, is hoisted onto an altar in the basilica apse.

At the apse of the church is the Triumph of the Chair of Saint Peter (1666) by Bernini, a focus of the Feast of Cathedra Petri celebrated annually on February 22 in accordance to the calendar of saints. The triumph is topped by a yellow window in which is a dove, portraying the Holy Spirit, surrounded by twelve rays, symbolising the apostles. Beneath it is the bronze encasing of the relic of the chair of St. Peter, given to the Vatican from Charles the Bald in 875. To the right of the chair are St Ambrose and St Augustine (fathers of the Latin church), and to the left are St Athanasius and St John Chrysostom (fathers of the Greek church). Further to the right is the monument to Urban VIII, by Bernini, and further to the left is the monument to Paul III.